Cardiotocography Interpretation Research Articles

Rational approach to electronic fetal monitoring during labour in 'all' resource settings

Electronic fetal monitoring (EFM) involves the use of cardiotocograph (CTG) to asses fetal wellbeing during labour in order to detect intrapartum fetal hypoxia early so as to institute timely and appropriate action. Indeed, when CTG was introduced into obstetric practice in the 1960s, it was expected to prevent perinatal brain injury and reduce the incidence of short term (neonatal admissions, seizures and neonatal deaths) and long term (cerebral palsy, learning difficulties) that arise secondary to intrapartum hypoxic insults. Unfortunately, although the rates of caesarean sections have dramatically increased over the last 40 years, there has been virtually no change in cerebral palsy rates. However, increasing caesarean section rates have contributed to maternal morbidity and mortality, including rising incidence of morbidly adherent placentae (placenta accrete, increta and percreta). Apart from a high 'false positive' rate of CTG, failure to appreciate the pathophysiology of fetal heart rate changes by the clinicians have contributed to increased operative deliveries, without any substantial improvements in neonatal outcomes. Hence, a rational approach is warranted in the use and interpretation of CTGs to improve maternal and fetal outcomes, in all settings, irrespective of the availability of additional tests of fetal wellbeing such as fetal blood sampling (FBS), fetal electrocardiograph (ST analyser or STAN), fetal pulse oximetry or scalp lactate. DOI: <a href="http://dx.doi.org/10.4038/sljog.v32i4.3988">http://dx.doi.org/10.4038/sljog.v32i4.3988</a> <em>SLJOG </em>2010; 32(4): 77-84

“Every case of asphyxia can be used as a learning example”. Conclusions from an analysis of substandard obstetrical care

To propose suggestions for improvements in care based on conclusions from studies on low Apgar scores and substandard care during labor. Studies on infants with low Apgar scores in a general obstetric population 2004-2006 and claims for financial compensation on the behalf of infants, based on the suspicion that substandard care in conjunction with childbirth has caused severe asphyxia or neonatal death in Sweden 1990-2005. The most common flaws were related to insufficient fetal surveillance, defective interpretation of cardiotocography (CTG) tracings, not acting in a timely fashion on abnormal CTG, and the incautious use of oxytocin. Besides, in half of the infants a suboptimal mode of delivery added further trauma to the already asphyxiated infant. Additionally, resuscitation was unsatisfactory in many of these infants. The most critical flaw was defective compliance with the guidelines concerning ventilation and the early paging of skilled personnel in cases of imminent asphyxia or known complications during labor. In many case reports, the documentation of the neonatal resuscitation was insufficient to enable accurate and reliable evaluation. Examples of proposed improvements in care during labor are the introduction of a permanent educational atmosphere with aside time for daily educational rounds and discussion, cooperation around the use of standardized terminology in CTG interpretation, the cautious use of oxytocin, and the routine paging of a pediatrician before birth in cases of complicated delivery or imminent asphyxia. The proposed interventions need to be evaluated in clinical trials in the future.

ST Analysis of the Fetal ECG, as an Adjunct to Fetal Heart Rate Monitoring in Labour: A Review.

ST Analysis of the Fetal ECG, as an Adjunct to Fetal Heart Rate Monitoring in Labour: A Review.

Knowledge of Adverse Neonatal Outcome Alters Clinicians' Interpretation of the Intrapartum Cardiotocograph

Presumed intrapartum hypoxic events are commonly cited in malpractice cases in obstetrics. Clinical interpretation of the fetal heart rate, known in the United Kingdom as a cardiotocograph (CTG), tracing has a direct impact on classifying a specific tracing as abnormal. Interpretation by clinicians of various types of deceleration in a tracing is subjective, and there have been frequent reports of inconsistencies related to CTG interpretation. The aim of this study was to test the hypothesis that existing knowledge of a severe obstetrical outcome by experienced clinicians would affect their interpretation of CTG tracings and that absence of such prior knowledge would result in a different classification of outcome. A database of previously recorded intrapartum CTGs from a published study was used to sequentially select tracings of 20 cases with newborn umbilical artery pH <7.05 and 20 cases with arterial pH >7.20. All CTGs were recorded with a scalp electrode in singleton fetuses at >36 weeks of gestation. Individual tracings of the 40 cases were analyzed by 5 experienced obstetricians in different maternity hospitals according to the International Federation of Gynecology and Obstetrics guidelines. Clinicians analyzed the tracings twice (first and second round) without knowing the purpose of the study or that the tracings were the same. No information on neonatal outcome was provided to the clinicians in the first round. Two months later in the second round, the clinician reanalyzed the 40 tracings, but the order was changed and information on the arterial pH in each case was provided. The primary study outcome measures were differences between the 2 rounds with respect to the identification of fetal heart rate accelerations, decelerations, variability, and overall classification. Clinicians who examined tracings of cases with artery pH <7.05 in the second round reported a significantly larger number of repetitive decelerations (P < 0.001) and reduced variability (P = 0.001) as well as a larger number of pathological classifications (P = 0.002); variable decelerations were identified less frequently (P = 0.008). Among the cases with normal pH analyzed in the second round, fewer were identified as having prolonged decelerations (P = 0.013) and no accelerations (P = 0.013), but more had pronounced decelerations (P = 0.031) and reduced variability (P = 0.007); there was also a reduction in pathological classification that did not meet statistical significance (P = 0.051). These findings show that prior knowledge of a low umbilical artery pH is associated with increased identification of intrapartum CTG as abnormal, primarily due to differences in evaluation of decelerations and variability.

Intra- and Interobserver Variability of Intrapartum Cardiotocography: A Multicenter Study Comparing the FIGO Classification with Computer Analysis Software

Objective: To evaluate and compare the computer analyzing software system with subjective interpretation using the FIGO classification of intrapartum cardiotocograms. Methods: Twenty-four obstetricians and 19 midwives from 3 hospitals [19 junior (≤3 years) and 24 senior (>3 years) experience] participated in this study. Forty-three doctors and midwifes interpreted intrapartum cardiotocographic (CTG) readings from 12 parturients without knowing the clinical outcome. Two CTG readings were repeated for evaluation of the intraobserver variability. Inter- and intraobserver agreement in CTG interpretation using the FIGO score and the computer analyzing software was assessed via proportions of agreement (Pa), with 95% confidence intervals. The level of inter- and intraobserver agreement was analyzed by calculating Pa values for CTG baseline, variability, accelerations and decelerations. Results: In total, for all parameters of the FIGO classification, Pa was very low. The highest 95% confidence level of Pa was found for the baseline parameter (0.49–1.01), and the lowest for the parameter acceleration. No significant difference was seen between obstetricians and midwifes as well as between junior and senior experience. In assessments of normal cases, the Pa were significantly higher than in pathological readings. Conclusion: Computer analyzing software can reduce the high inter- and intraobserver variability; however, further studies are needed to find out whether this can improve fetal outcome and reduce the number of Cesarean sections.

Evaluation and impact of cardiotocography training programmes: a systematic review

The interpretation and management of cardiotocography (CTG) tracings are often criticised in obstetric malpractice cases. As a consequence, regular CTG training has been recommended, even though little is known about the effect of CTG training. To perform a systematic review of the existing literature on studies on CTG training in order to assess educational strategies, evaluation of training programmes, and impact of training programmes. The Medline database was searched to identify studies describing and/or evaluating CTG training programmes. The literature search resulted in 409 citations. Twenty studies describing and evaluating CTG training programmes were included. There was no restriction on study design. Data regarding study design, study quality, educational strategies used for training in CTG interpretation and decision making, target groups, number of participants, methods used for evaluation, quality of evaluation, level of evaluation and results of training was extracted from 20 articles, and analysed using Kirkpatrick's four-level model for the evaluation of education. Training was associated with improvements on all Kirkpatrick levels, resulting in increased CTG knowledge and interpretive skills, higher interobserver agreement, better management of intrapartum CTG, and improved quality of care. Computer-based training (CBT) might be less time-consuming than classroom teaching. Clinical skills seem to decrease faster than theoretical knowledge. Training can improve CTG competence and clinical practise. Further research on CBT, test-enhanced learning and long-term retention, evaluation of training and impact on clinical outcomes is recommended.

Cardiotocography and perinatal outcome in women with and without meconium stained liquor

There is little evidence linking meconium stained liquor to poor perinatal outcome and clear amniotic fluid is frequently considered a reassuring sign during labour. To determine whether there are any differences in cardiotocography (CTG) tracings and perinatal outcomes in women with meconium stained compared with those with clear liquor in labour. A prospective cohort study. The Aga Khan University Hospital, Nairobi. Seventy seven women presenting in labour were studied. Thirty six had meconium stained liquor and 41 had clear liquor. Initial and intrapartum CTG was done. Perinatal and maternal outcomes determined were birth weights, Apgar scores, admission due to foetal indications and puerperal sepsis. CTG interpretation was based on RCOG/NICE guidelines-2001. SPSS 12.0.1 was used for all analyses. Variable decelerations were the most common foetal heart rate patterns. In the initial CTG, suspicious (RR 1.033, 95% CI: 0.515 - 2.073), and pathologic (RR 1.490, 95% CI: 0.928-2.393) patterns were increased in the meconium stained group. In the intrapartum CTG, pathologic pattern was increased in women with meconium stain liquor (RR 1.096, 95% CI: 0.650-1.847). Apgar score of <7 was likely if the initial base line rate was abnormal (RR 1.357, 95% CI: 0.139 -1.009, irrespective of the state of liquor. Meconium staining of liquor was associated with Caesarean delivery (RR = 1.357, 95% CI: 1.010-1.823; P-value 0.042). There was no significant difference in the mean birth weights of the infants born to women in both groups (3359.72 grams and 3260.24 grams respectively, P = 0.282). One minute Apgar score in both groups was not significantly (RR 0.390, 95% CI:0.131-1.1611). The suspicious and pathologic tracings were increased in the meconium stained liquor group. There was no significant difference in the Apgar scores in both groups of women. Meconium staining of liquor was significantly associated with Caesarean delivery.

A randomised clinical trial of intrapartum fetal monitoring with computer analysis and alerts versus previously available monitoring

BackgroundIntrapartum fetal hypoxia remains an important cause of death and permanent handicap and in a significant proportion of cases there is evidence of suboptimal care related to fetal surveillance. Cardiotocographic (CTG) monitoring remains the basis of intrapartum surveillance, but its interpretation by healthcare professionals lacks reproducibility and the technology has not been shown to improve clinically important outcomes. The addition of fetal electrocardiogram analysis has increased the potential to avoid adverse outcomes, but CTG interpretation remains its main weakness. A program for computerised analysis of intrapartum fetal signals, incorporating real-time alerts for healthcare professionals, has recently been developed. There is a need to determine whether this technology can result in better perinatal outcomes.Methods/designThis is a multicentre randomised clinical trial. Inclusion criteria are: women aged ≥ 16 years, able to provide written informed consent, singleton pregnancies ≥ 36 weeks, cephalic presentation, no known major fetal malformations, in labour but excluding active second stage, planned for continuous CTG monitoring, and no known contra-indication for vaginal delivery. Eligible women will be randomised using a computer-generated randomisation sequence to one of the two arms: continuous computer analysis of fetal monitoring signals with real-time alerts (intervention arm) or continuous CTG monitoring as previously performed (control arm). Electrocardiographic monitoring and fetal scalp blood sampling will be available in both arms. The primary outcome measure is the incidence of fetal metabolic acidosis (umbilical artery pH < 7.05, BDecf > 12 mmol/L). Secondary outcome measures are: caesarean section and instrumental vaginal delivery rates, use of fetal blood sampling, 5-minute Apgar score < 7, neonatal intensive care unit admission, moderate and severe neonatal encephalopathy with a marker of hypoxia, perinatal death, rate of internal monitoring, tracing quality, and signal loss. Analysis will follow an intention to treat principle. Incidences of primary and secondary outcomes will be compared between groups. Assuming a reduction in metabolic acidosis from 2.8% to 1.8%, using a two-sided test with alpha = 0.05, power = 0.80, and 10% loss to follow-up, 8133 women need to be randomised.DiscussionThis study will provide evidence of the impact of intrapartum monitoring with computer analysis and real-time alerts on the incidence of adverse perinatal outcomes, intrapartum interventions and signal quality. (Current controlled trials ISRCTN42314164)

Cardiotocography and ST analysis (STAN): a retrospective review

Fetal heart monitoring via cardiotocograph (CTG) has become integral to modern maternity care. The development of more sophisticated analytical techniques for fetal heart rate analysis has resulted in fetal monitoring systems that can add automated fetal electrocardiographic ST segment analysis (STAN) to the customary CTG information, providing continuous diagnostic information about the ability of the fetus to respond to the stress of labour. One such method, the STAN fetal monitoring system has demonstrated clear clinical utility, however, unidentified adverse outcomes for women monitored by STAN have been shown to be a result of poor CTG interpretation, delay in taking action and non-adherence to guidelines, as well as poor signal quality. This article presents some of the findings of a 3-year retrospective review of STAN cases following its introduction into a UK maternity unit. Findings corroborate other study results which have highlighted that CTG interpretation is often poor, although a key issue in this review was a failure by practitioners to actually classify the CTG. Review findings, however, suggest that this might be more often a record keeping problem than an issue of clinical competence. Interesting findings around epidural use require further investigation. The findings of this review have clear implications for training and practice not only in units where STAN is used but more broadly.

Foetal heart rate variability frequency characteristics with respect to uterine contractions

Monitoring foetal health is important to appropriately plan pregnancy management and delivery. Cardiotocography (CTG) is one of the most employed diagnostic techniques. Because CTG interpretation still lacks of complete reliability, new methods of interpretation and parameters are necessary to further support physicians’ decisions. To this aim, indexes related to variability of foetal heart rate (FHRV) are particularly studied. Frequency components of FHRV and their modifications can be analysed by applying a time-frequency approach, which allows for a distinct understanding of the spectral components related to foetal reactions to internal and external stimuli and their change over time. Being uterine contractions (UC) strong stimuli for the foetus and his autonomic nervous system (ANS), it is worth exploring the FHRV response to UC. This study analysed modifications of FHRV frequency characteristics with respect to 108 UC (relative to 35 healthy foetuses). Results showed a statistically significant (t-test, p < 0.01) power increase of the FHRV in both LF and HF bands in correspondence of the contractions. Moreover, we observed a shift to higher values of the maximum frequency contained in the signal corresponding to the power increase. Such modifications of the FHRV power spectrum can be a sign of ANS reaction and therefore represent additional, objective information about foetal reactivity and health during labour.

Role of Elaborate Cardiotocography (CTG) in Pregnancy Management

Background: Elaborate Cardiotocography (CTG) is the most commonly used test for antepartum and intrapartum fetal surveillance because it gives information via the cerebro-cardiac response of fetal cerebral activity, which is modified by the hypoxia. Objective: This study was designed to compare the perinatal outcomes among the normal and abnormal CTG groups. Method: It was a prospective observational study carried out in the Department of obstetrics, BSMMU during the period July 2006 to July 2008. Hundred consecutive normal and hundred consecutive abnormal CTC tracings were collected from patients who were advised to perform CTG after admission. Both labour and non-labour patients were included. Interpretation of CTG was done based on FlGO recommendation (1987). Pregnancy and neonatal data were obtained and the findings were correlated with the FHR tracing. Statistical analysis was carried out by student's unpaired t-test, X 2 and Z-test. Level of significance was set at P value < 0.05. Results: Out of 100 abnormal CTG, 30% had tachycardia, 42% had deceleration, 38% was non reactive, 4% had absence beat-to-beat variability and 4% had fetal bradycardia. There was significantly higher caesarean delivery, lower apgar score, higher requirement of neonatal resuscitation and admission at neonatal unit and higher perinatal death among the abnormal CTG group. The abnormal fetal outcome was found highest in heart rate deceleration group. Conclusion: CTG can be continued as a good screening test of fetal surveillance but it is not the sole criteria to influence the management of high-risk pregnancies. Abnormal CTG should be supplemented with other test before intervention. Key words: CTG; Perinatal outcome. DOI: 10.3329/bsmmuj.v2i1.3706 BSMMU J 2009; 2(1): 18-24

Analysis of 127 peripartum hypoxic brain injuries from closed claims registered by the Danish Patient Insurance Association

One of the most feared complications in medicine is hypoxic brain damage to a newborn. The authors investigated the circumstances of registered peripartum hypoxic brain injuries in order to identify potential opportunities to improve patient safety and prevent injuries. The authors retrospectively investigated peripartum hypoxic brain injuries registered by the Danish Patient Insurance Association. From 1992 to 2004, 127 approved claims concerning peripartum hypoxic brain injuries were registered and subsequently analysed. Thirty-eight newborns died, and a majority of the 89 surviving children suffered from major handicaps, primarily cerebral palsy. In 69 of the cases, misinterpretation of or late action on an abnormal cardiotocography (CTG) were the reasons for the majority of the hypoxic brain injuries. All injuries could potentially have been avoided using established obstetric practice. CTGs are often misinterpreted. In the authors' opinion, education and training in CTG interpretation is essential. The use of ST-analysis of the fetus ECG (STAN) could probably reduce the number of these injuries.

Review of the first 1502 cases of ECG‐ST waveform analysis during labour in a teaching hospital

To assess the impact of introduction of the STAN monitoring system. Prospective observational study. Tertiary referral labour ward, St George's Hospital, London. High-risk term pregnancies. We report all consecutive cases of intrapartum monitoring using the STAN S 21 fetal heart monitor. Cases with adverse neonatal outcome were evaluated in relation to the ST waveform analysis and cardiotocography (CTG). Cord artery metabolic acidosis, neonatal encephalopathy (NNE) and reasons behind cases with poor outcome. Between 2002 and 2005, there were 1502 women monitored by STAN. Based on combined STAN analysis in the 1502 women, action was indicated in 358 women (23.8%), while in 1108 women (73.8%) no action was indicated. Traces were not interpretable in 36 women (2.4%). Of the 836 cases (55.7%) where cord blood gases were available, there were 23 cases (2.8%) of metabolic acidosis and 16 of these (70%) were identified by STAN. Overall, there were 14 cases of NNE monitored by STAN. Retrospective analysis of these highlights human errors, such as poor CTG interpretation, delay in taking appropriate action and not following the guidelines. Our experience suggests the need for more intense training on interpretation of CTG and strict adherence to guidelines.

Fetal electrocardiogram: ST waveform analysis in intrapartum surveillance

ST waveform analysis of fetal electrocardiogram (ECG) for intrapartum surveillance (STAN) is a newly introduced method for fetal surveillance. The purpose of this commentary is to assist in the proper use of fetal ECG in combination with cardiotocography (CTG) during labour. Guidelines and recommendations concerning CTG and ST waveform interpretation and classification are stated that were agreed on by the European experts on ST waveform analysis for intrapartum surveillance during a meeting in Utretcht, the Netherlands in January 2007.

Cardiotocography revisited

The interpretation of cardiotocograph (CTG) evidence is a crucial feature in many legal claims. A case heard in the Court of Session in Edinburgh in June (Lowe v Yorkhill) is of interest to midwives for three reasons in particular. The first concerns the ability to assess intrapartum CTG recordings; the second is the use of documentary evidence that can be used when deciding whether clinical actions were negligent or not; and the third concerns the advisability of experts criticising the actions or opinions of those in another profession.

A randomised-controlled trial evaluating a fetal monitoring education programme

to evaluate the effectiveness of a fetal monitoring education programme on midwives' fetal monitoring knowledge and intrapartum cardiotocograph interpretation skills. two group, before-after, randomised-controlled trial. two maternity hospitals in the Republic of Ireland. 55 midwives were randomly assigned to either the experimental group (n=27) or the control group (n=28). the experimental group participated in a 1.5 hr fetal monitoring education programme, whereas the control group attended an alternative education programme consisting of a non-fetal-monitoring-related video presentation. the primary outcomes of interest were fetal monitoring knowledge and intrapartum cardiotocograph interpretation skills test. in the fetal monitoring knowledge post-test, the median percentage correct responses for the control and experimental groups were 56% (IQR 18.75) and 88% (IQR 12.5), respectively. This difference, 31.2%, was statistically significant (U=78.5, 95.1% CI -31.25 to -18.75, p<0.001). In the intrapartum cardiotocograph interpretation skills post-test, the median percentage correct responses for the control and experimental groups were 55.6% (IQR 16.7) and 66.7% (IQR 22.2), respectively. This difference, of 11.1%, was statistically significant (U=186, 95.2% CI -16.67 to -5.56, p<0.001). attendance at a short (1.5 hr), in-service fetal monitoring education programme can increase midwives' fetal monitoring knowledge and cardiotocograph interpretation skills. The availability of in-service fetal monitoring education programmes is sporadic, often less than recommended, and is a cause for concern.

Does Training in Obstetric Emergencies Improve Neonatal Outcome?

The investigators report a retrospective observational study carried out at a tertiary referral maternity unit within a teaching hospital to learn whether training in how to manage obstetric emergencies improves neonatal outcomes. The cohort consisted of 19,460 singleton infants born in the years 1998 through 2003. Those with a gestational age of less than 37 weeks were excluded. The participants, a multidisciplinary group including midwives, obstetricians, and anesthetists, took part in a 1-day training course. The major outcomes were the rate of 5-minute Apgar scores of 6 or higher and the occurrence of neonatal hypoxic–ischemic encephalopathy (HIE). The morning session emphasizes cardiotocographic interpretation and uses a range of teaching methods, including a workbook with cases to be completed before the course, lectures on guidelines for fetal monitoring, small group case discussions, and instruction in documentation using a structured reportorial format. The afternoon session features obstetric emergency drill stations dealing with shoulder dystocia, postpartum hemorrhage, eclampsia, twin birth, breech presentation, adult resuscitation including cardiopulmonary resuscitation, and neonatal resuscitation. An in-house multiprofessional steering group developed all materials for the course. Women in the posttraining group (2001–2003) were older than those in the pretraining group (1998–1999) and more often nulliparous. They also were likelier to have an emergency cesarean section. The 2 groups were similar with respect to gestational age at the time of delivery and neonatal birth weights. There were significant reductions in the rates of both abnormal Apgar scores and HIE. Moderate and severe HIE tended to be less frequent in the posttraining phase of the study, but not significantly so. Rates of antepartum and intrapartum intrauterine deaths did not change during the course of the study. These findings suggest that specific training of relevant personnel in how best to manage obstetric emergencies is a practical idea and may in fact improve neonatal outcomes, specifically elevated 5-minute Apgar scores and the risk of HIE. This is the first time that an educational intervention has been associated with clinically important and lasting improvement in neonatal status.

Intrapartum cardiotocography – the dilemma of interpretational variation

To evaluate and compare interobserver variation in interpretation of intrapartum cardiotocograms. Fifteen senior (experience >4 years) and 16 junior (experience < or =4 years) obstetricians from 10 delivery units. Thirty-one obstetricians interpreted intrapartum cardiotocographic (CTG) readings from 22 parturients. Inter-observer agreement in CTG interpretation and decision-making was assessed via proportions of agreement (Pa), with 95% confidence intervals (CI). The level of inter-observer agreement was analyzed by calculating Pa values for CTG baseline, variability, early, variable and late decelerations, uterine tonus, power of contractions, hypertonus and clinical decision. In assessments of normal cases the Pa were acceptable or good (0.63-0.82) as regards all CTG interpretation elements except for the power of contractions (0.24), but in assessments of abnormal cases the Pa values were lower (0.18-0.60). As regards clinical decisions, a higher Pa was found in cases without recommendation for intervention (0.63, 95% CI 0.62-0.64) than in cases with such recommendation (0.55, 95% CI 0.54-0.56). The Pa in the abnormal cases was better among senior than among junior obstetricians. Inter-observer variation in interpretation of abnormal CTG readings and recommendations for intervention is relatively wide. To improve reliability, uniform classification and standardized training in CTG interpretation are needed, as well as increased use of computerized CTG.

Midwives’ visual interpretation of intrapartum cardiotocographs: intra‐ and inter‐observer agreement

This paper reports an examination of intra- and inter-observer agreement in midwives' visual interpretation of intrapartum cardiotocographs (CTGs). The issue of intra- and inter-observer agreement in the interpretation of CTG interpretation has serious implications for the validity of electronic fetal heart rate monitoring and subsequent decisions on intrapartum management. However, no studies were found that assessed intra- and inter-observer agreement in midwives' interpretations of CTG tracings. Twenty-eight midwives independently interpreted three intrapartum CTG tracings on two separate occasions using a self-administered Cardiotocograph Interpretation Skills Test. Inter-rater agreement in interpretation was assessed by cross-tabulating the two sets of raw data obtained at time 1 and time 2 and computing Cohen's Kappa (kappa). Intra-rater agreement was assessed by computing kappa for each rater with the two sets of raw data (time 1 and time 2) obtained from each individual. The data were collected in 2000. Overall intra-rater agreement ranged from 'fair to good' (kappa = 0.48) to 'excellent' (kappa = 0.92). Raters' classifications altered in 18% (n = 5) of cases for the normal tracing, in 29% (n = 8) for the suspicious tracing and in 11% (n = 3) for the pathological tracing. Inter-rater agreement was fair to good, with kappa statistics ranging from 0.65 to 0.74, respectively. Agreement was highest in the classification of decelerations (kappa = 0.79) and lowest in the assessment of baseline variability (kappa = 0.50). Overall inter-rater agreement was highest in the suspicious tracing (kappa = 0.77, excellent) and lowest in the normal tracing (kappa = 0.54, fair to good). Inter- and intra-observer variability are intrinsic characteristics of the interpretation of intrapartum CTGs. Levels of agreement revealed degrees of variation that expose room for improvement. Efforts are needed to reduce inter- and intra-observer variation in interpretation of intrapartum CTG tracings. In addition, research should focus on the development and evaluation of non-invasive, low observer variability methods of intrapartum assessment of fetal well-being. The subjectivity of CTG interpretation and inconsistencies in interpretation should also be considered in intrapartum management, clinical audit and in medico-legal settings.

Antepartum cardiotocography: A study of fetal reactivity in frequency domain

Cardiotocography (CTG) is the most widely used diagnostic technique in clinical practice to monitor fetal health. Cardiotocographic recording also permits to assess maturation of the fetal autonomous nervous system (ANS): fetal heart rate (FHR) modifications may reveal ANS’ reactions to stimuli. To assess fetal reactivity, physicians evaluate specific clinical CTG parameters, generally, by means of visual inspection, thus depending on observer's expertise, with lack of reproducibility. Still nowadays, there is a very high intra- and inter-observer variation in the assessment of FHR patterns. More objective methods for CTG interpretation are of crucial importance. For adults, frequency analysis of heart rate variability (HRV) is a non-invasive and powerful method to investigate ANS activity. This frequency analysis can also be a valid support for a better knowledge of fetal ANS functional state and reactions. Indeed, fetal HRV is a good indicator of fetal well-being in non-stress conditions. Fetal reactivity is a very important CTG characteristic used to diagnose fetal distress, but its interpretation is still uncertain. The aim of this study is to characterise fetal reactivity proposing new fetal HRV frequency parameters to support a more exhaustive CTG analysis.